1. Field of the Invention
The present invention relates in general to window regulators, and more particularly, to the window regulators of a type that regulates a window pane installed in an automotive door having no sash.
2. Description of the Related Art
Hitherto, various types of window regulars have been proposed and put into practical use particularly in the field of automotive doors. One of them is shown in Japanese Patent Second Provisional Publication 3-23708. The window regulator of this publication is of a type that regulates a window pane installed in an automotive side door having no sash. The doors having no sash will be referred to as “sashless door” hereinafter for ease of description.
The window regulator of the publication generally comprises front and rear guide rails installed in a door, front and rear carrier units connected to lower portions of a window pane and slidably engaged with the front and rear guide rails, and an electric drive unit installed in a lower part of the door to drive the front and rear carrier units and thus the window pane to move upward and downward along the front and rear guide rails. The drive unit comprises an electric motor, a drum driven by the motor and a cable wire put around the drum. The cable wire extends around the front and rear guide rails and has two portions secured to the front and rear carrier units. When the motor is energized to run, the front and rear carrier units and thus the window pane are moved upward or downward along the front and rear guide rails.
When, in case of a sashless door, the door is in its closed position with its window pane kept fully raised, a peripheral portion of the window pane is pressed against a weather strip fixed to a vehicle body thereby to achieve a water tight sealing therebetween.
As is known, under a high speed cruising of motor vehicles, a reduced pressure zone is inevitably produced around an outside surface of the window pane. Production of such reduced pressure zone biases the window pane to incline outward increasing the possibility of lowering the air-tightness between the window pane and the weather strip.
In order to suppress or minimize such undesirable outward inclination of the window pane, various measures have been put into practical use. One is to produce the guide rails especially the rear guide rail by a thicker steel plate and closely engage the rear carrier unit with the rear guide rail. One is to arrange the front and rear guide rails to assume an exaggerated angle relative to the door by taking into consideration a possible outward inclination of the window pane that would occur during a high speed cruising.